Do you want the POS integrated with your EFTPOS terminal, or are you happy re-keying the amount into a separate EFTPOS terminal?

You've got a lot more flexibility with the latter.

That said, Vend has a free tier that might work for you (and Vend integrates with quite a few EFTPOS terminals). The free tier is limited in terms of users, products, registers etc but you should be manageable for a bar. The number of products (10) might catch you out depending on how many boutique beers you stock though.

Lots of advantages to you with a SaaS product too (i.e. not being the only person that gets called when the system you set up isn't working).